Field of the Invention
The present invention relates to a method for detecting the switching state of a stop switch at a switch terminal of an ignition device for an internal combustion engine and an ignition device operating accordingly.
Description of the Background Art
It is basically known from DE 197 36 032 B4 and DE 10 2004 059 070 A1 to provide an ignition module or a magnetic ignition circuit (magnetic ignition circuit or condenser ignition device) with an external stop switch. The stop switch acts on power electronics (control unit) and in the closed state prevents the generation of an ignition spark.
In a method disclosed in EP 2 330 606 A1, a voltage pulse or a voltage signal is applied at a stop connection for the stop switch of a magnetic ignition circuit for the purpose of cleaning the contacts of the stop switch. The appropriate voltage pulse is generated by rectifying a voltage signal, which arises during the discharge of a power storage device. It is also known from this patent to use a medium voltage pulse concurrently as a stop switch sampling or for evaluating the state of the stop switch, i.e., whether its switch contacts are open or closed. For this purpose, a digital controller of the known magnetic ignition system can measure the voltage at the stop switch during the medium voltage pulse, and the opened state of the stop switch can be inferred if a specific level or a voltage value predetermined for the controller for a voltage comparison is exceeded, whereas a closed state of the stop switch can be inferred when values fall below the level or the predetermined voltage value.